Thin film capacity element-use composition, high-permittivity insulation film, thin film capacity element and thin film multilayer capacitor

ABSTRACT

A thin-film capacitor( 2 ) in which a lower electrode( 6 ), a dielectric thin-film( 8 ), and an upper electrode( 10 ) are formed in order on a substrate( 4 ). The dielectric thin-film( 8 ) is made of a composition for thin-film capacitance devices. The composition includes a bismuth layer-structured compound whose c-axis is oriented vertically to the substrate surface and which is expressed by a formula: (Bi 2 O 2 ) 2+ (A m−1 B m O 3m+1 ) 2− , or Bi 2 A m−1 B m O 3m+3  wherein “m” is an odd number, “A” is at least one element selected from Na, K, Pb, Ba, Sr, Ca and Bi, and “B” is at least one element selected from Fe, Co, Cr, Ga, Ti, Nb, Ta Sb, V, Mo and W. Even if the dielectric thin-film is made more thinner, the dielectric constant is relatively high, and the loss is small. The leak characteristics are excellent, the temperature characteristics of the dielectric constant are excellent, the break-down voltage is improved and the surface smoothness is excellent.

FIELD OF THE INVENTION

[0001] The present invention relates to compositions for thin-filmcapacitance device, high-dielectric constant insulating film, thin-filmcapacitance device, and thin-film multilayer capacitor. Moreparticularly, the invention relates to compositions for thin-filmcapacitance device used as dielectric thin-films or so for thin-filmcapacitance device of every kind, such as condenser or capacitor havingconductor-insulator -conductor structure and thin-film capacitancedevice such as condenser or capacitor wherein said compositions forthin-film capacitance device is used as dielectric thin-film.

DESCRIPTION OF THE RELATED ART

[0002] In recent years, in the field of Electronic Component, along withthe tendencies of higher density and higher integration of electroniccircuit, circuit devices essential to electronic circuit of every kind,such as capacitance device, are desired for more compact body and higherperformance.

[0003] For instance, thin-film capacitor using a layer dielectricthin-film, in respect of integrated circuit with active component suchas transistor, is delayed for more compact body. This is a factor ofobstruction for realizing ultrahigh integrated circuit. More compactbody for thin-film capacitor is delayed because dielectric constant ofdielectric materials used for the thin-film capacitor was low.Accordingly, in order to realize more compact body and relatively highcapacitance, the use of dielectric materials with high dielectricconstant is important.

[0004] Moreover, in recent years, from the point of capacity density,conventional SiO₂ and Si₃N₄ multilayer films are not good enough to beused for capacitor materials of advanced DRAM(gigabit generation), andmaterials with more higher dielectric constant are being noticed. Inthese materials, the application of TaOx(ε=˜30) has been mainlyconcerned, but other materials have actively come into develop.

[0005] On the other hand, as dielectric materials having relatively highdielectric constant, (Ba, Sr)TiO₃(BST) or Pb(Mg_(1/3) Nb_(2/3))O₃(PMN)are known.

[0006] Therefore, composing thin-film capacitance device by the use ofthese kinds of dielectric materials, more compact body may be expected.

[0007] However, when these kinds of dielectric materials are used, bymaking the dielectric film thinner, dielectric constant lowered in somecases. And due to pores that appear on dielectric film by making thedielectric film thinner, leak characteristic and break-down voltagedeteriorated in some cases. Further, formed dielectric film deterioratedin surface smoothing property and change rates of dielectric constant totemperature also tends to deteriorate in some cases. Further, in recentyears, since lead compound such as PMN have large influence onenvironment, high-storage capacitor without lead is desired.

[0008] To the contrary, in order to realize more compact body and higherstorage of multilayer ceramic capacitor, the thickness of each layer fordielectric layer is desired to be further thinner as much aspossible(further thinner layer) and the number of laminated layers fordielectric layer at a fixed size is desired to improve as much aspossible(multiple layers).

[0009] However, by the use of sheet method(A method comprising thefollowing steps. Dielectric green sheet layer is formed such as bydoctor blade method on carrier film using dielectric layer paste. And onthe dielectric green sheet layer, internal electrode paste is printed byfixed pattern. Afterwards, these are peeled off and laminated by eachlayer.), when producing multilayer ceramic capacitor, it is impossibleto form thinner dielectric layer than ceramic source material powder.Besides, short or breaking internal electrode problems due to dielectriclayer defects, the dielectric layer was difficult to be further thinner,for instance, 2 μm or less. Moreover, when dielectric layer of eachlayer is further thinner, the number of laminated layers had its limit.Further, by the use of printing method(A method, using screen printingmethod or so, which plural number of dielectric layer paste and internalelectrode paste are alternately printed on carrier film and then thecarrier film is peeled off.), when producing multilayer ceramiccapacitor, the same problem exists.

[0010] Due to these causes, producing more compact body and relativelyhigh capacitance of multilayer ceramic capacitor had its limit.

[0011] Accordingly, in order to overcome these problems, variousproposes are done(ex. Japanese Unexamined Patent Publications No.56-144523, No. 5-335173, No. 5-335174, No. 11-214245 andNo.2000-124056).

[0012] These publications disclose methods to produce multilayer ceramiccapacitor which dielectric thin-films and electrode thin-films arealternately laminated using thin-film forming method of every kind suchas CVD method, evaporation method or sputtering method.

[0013] However, dielectric thin-film formed by the methods described inthese publications have bad surface smoothing property and when too manyof the dielectric thin-film are layered, electrode may short-circuit insome cases. Accordingly, the number of laminated layers of at most 12 to13 or so can only be produced, so that even capacitor was capable ofrealizing more compact body, it was not capable of higher capacitance.

[0014] Further, as shown in an reference “Particle orientation forbismuth layer-structured ferroelectric ceramic and application to itspiezoelectric and pyroelectric materials” by Tadashi Takenaka, doctoraldissertation of engineering at Kyoto University(1984), pages 23 to 77 ofArticle 3, it is known that following composition composes a bulkbismuth layer-structured compound dielectric obtained by sinteringmethod; a composition expressed by formula:(Bi₂O₂)²⁺(A_(m−1)B_(m)O_(3m+1))²⁻ or Bi₂ A_(m−1)B_(m)O_(3m+3) whereinsymbol m is selected from positive numbers of 1 to 8, symbol A is atleast one element selected from Na, K, Pb, Ba, Sr, Ca and Bi and B is atleast one element selected from Fe, Co, Cr, Ga, Ti, Nb, Ta Sb, V, Mo andW.

[0015] However, this article did not describe under which condition(ex.the relation between substrate surface and degree of c-axis orientation)the compositions shown by abovementioned formula are made furtherthinner(ex. 1 μm or less) in order to obtain the following thin-film. Athin-film which is, when made further thinner, capable of providingrelatively high dielectric constant and low loss, and also superior leakproperty, break-down voltage, temperature characteristic of dielectricconstant and surface smoothness property.

DISCLOSURE OF THE INVENTION

[0016] The object of the invention is to provide compositions forthin-film capacitance device that are, even made further thinner,capable of providing relatively high dielectric constant and low-loss,and also superior leak property, break-down voltage, temperaturecharacteristic of dielectric constant and surface smoothness property,and to provide thin-film capacitance device using the compositions.Also, another object of the present invention is, by using thesethin-film capacitance device compositions as dielectric thin-film, toprovide a thin-film multilayer capacitor which can give more compactbody and relatively high capacitance. Further, the present invention isalso to provide high-dielectric constant insulating film which provide,even made further thinner, relatively high dielectric constant andlow-loss, also superior leak property, break-down voltage, temperaturecharacteristic of dielectric constant and surface smoothness property.

[0017] The inventors of the present invention have earnestly consideredof dielectric thin-film materials used for capacitor and its crystalstructure. As a result, using a bismuth layer-structured compound havingspecific composition, moreover, by orientating c-axis([001]orientation)of the bismuth layer-structured compound vertically to substrate surfaceand composing dielectric thin-film as thin-film capacitance devicecompositions, that is, by forming c-axis orientation film(thin-filmnormal is parallel to c-axis) of bismuth layer-structured compound on tothe substrate surface, it was found that thin-film capacitance devicecompositions and thin-film capacitance device using the compositionscould be provided. The thin-film capacitance device compositions are,even made further thinner, relatively high dielectric constant andlow-loss(low tan δ) can be provided, and also superior leak property,break-down voltage, temperature characteristic of dielectric constantand surface smoothness property. Moreover, by the use of these thin-filmcapacitance device compositions as dielectric thin-film, it was foundthat number of laminated layers can be increased and thin-filmmultilayer capacitor which can give more compact body and relativelyhigh capacitance can be provided. This brought completion of the presentinvention. Furthermore, by using these compositions as high dielectricconstant insulating film, it was found that the compositions can beapplied other than as thin-film capacitance device, which broughtcompletion of the present invention.

[0018] Therefore, thin-film capacitance device compositions according tothe present invention including a bismuth layer-structured compoundwhose c-axis is oriented vertically to a substrate surface wherein saidbismuth layer-structured compound is expressed by a formula:(Bi₂O₂)²⁺(A_(m−1)B_(m)O_(3m+1))²⁻ or Bi₂A_(m−1)B_(m)O_(3m+3) in whichsymbol “m” is selected from odd numbers, symbol “A” is at least oneelement selected from Na, K, Pb, Ba, Sr, Ca and Bi and symbol “B” is atleast one element selected from Fe, Co, Cr, Ga, Ti, Nb, Ta Sb, V, Mo andW.

[0019] “Thin-film” according to the invention is a film for materialswhose thickness is about several Å to several μ m and formed bythin-film forming method of every kind. “Thin-film” excludes athick-film bulk whose thickness is about several hundreds μ m or moreand formed by sintering method. Thin-film includes continuous film whichcovers fixed area continuously and also intermittent film which coversoptional intervals intermittently. Thin-film may be formed at a part ofsubstrate surface and may also be formed at the entire surface.

[0020] The thickness of dielectric thin-film(or high dielectric constantinsulating film) formed by thin-film capacitance device compositionsaccording to the invention is preferably 5 to 1000 nm. When at thisthickness, the present invention is quite effective.

[0021] The process of manufacturing thin-film capacitance devicecompositions according to the invention is not particularly limited butit can be manufactured by, for instance, using substrates of cubicsystem, tetragonal system, orthorhombic system, or monoclinic systemthat are [100] oriented, and forming thin-film capacitance devicecompositions including a bismuth layer-structured compound which isexpressed by a formula: (Bi₂O₂)²⁺(A_(m−1)B_(m)O_(3m+1))²⁻ orBi₂A_(m−1)B_(m)O_(3m+3) wherein symbol “m” is selected from odd numbers,symbol “A” is at least one element selected from Na, K, Pb, Ba, Sr, Caand Bi and symbol “B” is at least one element selected from Fe, Co, Cr,Ga, Ti, Nb, Ta Sb, V, Mo and W. In this case, the abovementionedsubstrate is preferably composed by single crystal.

[0022] Thin-film capacitance device of the invention is characterized ina thin-film capacitance device wherein lower electrode, dielectricthin-film and upper electrode are formed one by one on the substrate andsaid dielectric thin-film is composed of abovementioned thin-filmcapacitance device compositions of the invention.

[0023] Thin-film multilayer capacitor of the invention comprisingdielectric thin-films and internal electrode thin-films alternatelylayered on a substrate, wherein said dielectric thin-films are composedof abovementioned thin-film capacitance device compositions of theinvention.

[0024] According to the present invention, a bismuth layer-structuredcompound whose c-axis is oriented 100% vertically to the substratesurface, that is, a bismuth layer-structured compound whose degree ofc-axis orientation is 100%, which is particularly preferable. However,the degree of c-axis orientation may not be complete 100%.

[0025] Preferably, said bismuth layer-structured compound whose degreeof c-axis orientation is 80% or more, more preferably, 90% or more, mostpreferably, 95% or more. By improving the degree of c-axis orientation,the effect of the present invention improves.

[0026] Preferably, “m” in the formula composing said bismuthlayer-structured compound is 1, 3, 5 or 7, more preferably, 1, 3 or 5.This is due to the easiness of manufacturing.

[0027] Preferably, said thin-film capacitance device compositionsfurther include rare-earth element(at least one element selected fromSc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu).

[0028] Preferably said rare-earth element is “Re” and when said bismuthlayer-structured compound is expressed by formula:Bi₂A_(m−1−x)Re_(x)B_(m)O_(3m+3), said x is 0.4 to 1.8, more preferably,1.0 to 1.4. Including rare-earth element decreases leak current andshort ratio, and also Curie temperature can be −100° C. or more to 100°C. or less.

[0029] Preferably, said thin-film capacitance device compositions haveCurie temperature of −100° C. or more to 100° C. or less.

[0030] Preferably, thin-film multilayer capacitor of the invention, saidinternal electrode thin-film is composed of noble metal, base metal orconductive oxide.

[0031] At the thin-film capacitance device and thin-film multilayercapacitor of the invention, said substrate may be composed of amorphousmaterial. Lower electrode(or internal electrode thin-film) formed on thesubstrate is preferably [100] oriented. By forming lower electrode to[100] orientation, c-axis of a bismuth layer-structured compoundcomposing dielectric thin-film formed on the lower electrode can orientvertically to the substrate surface.

[0032] Thin-film capacitance device compositions of the invention anddielectric thin-film as their example are composed of c-axis orientedbismuth layer-structured compound having specific composition.

[0033] Thin-film capacitance device compositions composed of c-axisoriented bismuth layer-structured compound having specific compositionare, even when film thickness is made further thinner, relatively highdielectric constant(ex. more than 200) and low loss(tan δ is 0.02 orless) can be provided. They can also provide superior leak property(ex.leak current is 1×10⁻⁷ A/cm² or less and short ratio is 10% or less whenmeasured at 50 kV/cm electrolytic strength), improved break-downvoltage(ex. 1000 kV/cm or more), superior temperature characteristic ofdielectric constant(ex. average change rates of dielectric constant totemperature is within ±500 ppm/° C. at reference temperature of 25° C.)and superior surface smoothness property(ex. surface roughness: Ra is 2nm or less).

[0034] Further, thin-film capacitance device compositions according tothe present invention are, when its film thickness is made furtherthinner, relatively high dielectric constant can be provided. Moreover,due to the satisfactory surface smoothness, increasing number oflaminated layers for dielectric thin-film as said thin-film capacitancedevice compositions is capable. Therefore, by using the thin-filmcapacitance device compositions, thin-film multilayer capacitor that cangive more compact body and relatively high capacitance can be provided.

[0035] Further, thin-film capacitance device compositions and thin-filmcapacitance device of the invention are superior in frequencycharacteristic(ex. At specific temperature, ratio of dielectric constantvalue at high frequency domain of 1 MHz and those at lower than theabove frequency domain of 1 kHz is 0.9 to 1.1 in absolute value.) andalso in voltage characteristic (ex. At specific frequency, ratio ofdielectric constant value at measuring voltage of 0.1V and those atmeasuring voltage of 5V is 0.9 to 1.1 in absolute value).

[0036] Furthermore, thin-film capacitance device compositions of theinvention are superior in temperature characteristic for electrostaticcapacity(average change rates of the electrostatic capacity totemperature is within ±500 ppm/° C. at reference temperature of 25° C.).

[0037] For thin-film capacitance device, but not particularly limitedto, conductor-insulator-conductor structured condenser(ex. single layertyped thin-film capacitor or multilayer typed thin-film multilayercapacitor ) or capacitor(ex. such as for DRAM) are exemplified.

[0038] For thin-film capacitance device compositions, but notparticularly limited to, dielectric thin-film compositions for condenseror dielectric thin-film compositions for capacitor are exemplified.

[0039] High dielectric constant insulating film of the invention iscomposed of the same compositions as thin-film capacitance devicecompositions of the invention. High dielectric constant insulating filmof the invention can be used as, other than thin-film dielectric filmfor thin-film capacitance device or capacitor, gate-insulating film ofsemiconductor device or intermediate insulating film between gateelectrode and floating gate or so.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIG. 1 is a sectional view of an example for thin-film capacitorof the invention,

[0041]FIG. 2 is a sectional view of an example for thin-film multilayercapacitor of the invention,

[0042]FIG. 3 is a graph of frequency characteristic for capacitor sampleof example 9,

[0043]FIG. 4 is a graph of voltage characteristic for capacitor sampleof example 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] Below, the present invention will be explained based onembodiments shown in drawings.

[0045] First Embodiment

[0046] The present embodiment is described by exemplifying a thin-filmcapacitor forming a layer dielectric thin-film as thin-film capacitancedevice. As shown in FIG. 1, thin-film capacitor 2 according to anembodiment of the invention includes substrate 4, and on the substrate4, lower electrode thin-film 6 is formed. On lower electrode thin-film6, dielectric thin-film 8 is formed. On dielectric thin-film 8, upperelectrode thin-film 10 is formed.

[0047] Substrate 4 is composed of single crystal with high matchedlattice (ex. single crystal of SrTiO₃, MgO or LaAlO₃), amorphousmaterials(ex. glass, fused quartz or SiO₂/Si) and other materials(exZrO₂/Si or CeO₂/Si) or so. Particularly, composed of substrate orientedto such as [100] orientation e.g. cubic system, tetragonal system,orthorhombic system, or monoclinic system, are preferable. Thickness ofsubstrate 4 is not particularly limited but is about 100 to 1000 μm.

[0048] When using single crystal with high matched lattice as substrate4, lower electrode thin-film 6 is preferably composed of conductiveoxide, such as CaRuO₃ or SrRuO₃, or noble metal such as Pt or Ru, morepreferably, [100] oriented conductive oxide or noble metal. When usingsubstrate 4 which is [100] oriented, conductive oxide or noble metalwhich is [100] oriented can be formed on its surface. By composing lowerelectrode thin-film 6 with [100] oriented conductive oxide or noblemetal, degree of orientation to [001], that is, degree of c-axisorientation of dielectric thin-film 8 formed on the lower electrodethin-film 6 increases. This lower electrode thin-film 6 is formed bynormal thin-film forming method. However, it is preferable to be formedby physical vapor deposition method such as sputtering method or pulsedlaser deposition method(PLD) in which temperature of substrate 4 forforming lower electrode thin-film 6 on its surface is preferably 300° C.or more, more preferably 500° C. or more.

[0049] Lower electrode thin-film 6 using amorphous materials forsubstrate 4 can be composed of conductive glass such as ITO. When usingsingle crystal with high matched lattice as substrate 4, [100] orientedlower electrode thin-film 6 can easily be formed on the surface. Due tothis, degree of c-axis orientation of dielectric thin-film 8 formed onthe lower electrode thin-film 6 tends to increase. However, even usingamorphous materials such as glass for substrate 4, it is possible toform improved degree of c-axis orientation of dielectric thin-film 8. Inthis case, optimization of film formation condition for dielectricthin-film 8 is required.

[0050] As other lower electrode thin-film 6, noble metal such asgold(Au), palladium(Pd), Silver(Ag) or their alloys and also base metalsuch as Nickel(Ni), Copper(Cu) or their alloys can be used.

[0051] The thickness of lower electrode thin-film 6 is not limited butpreferably 10 to 1000 nm, more preferably 50 to 100 nm or so.

[0052] Upper electrode thin-film 10 can be composed of the same materialas said lower electrode thin-film 6. And the thickness can also be thesame.

[0053] Dielectric thin-film 8 is an example of thin-film capacitancedevice compositions of the invention, and include bismuthlayer-structured compound expressed by formula:(Bi₂O₂)²⁺(A_(m−1)B_(m)O_(3m+1))²⁻ or Bi₂A_(m−1)B_(m)O_(3m+3). Generally,bismuth layer-structured compound shows a laminar structure which upperand lower parts of laminar perovskite layer, which perovskite latticecomposed of (m−1) numbers of ABO₃ is ranged, are sandwiched by a pair ofBi and O layer. According to the present embodiment, the bismuthlayer-structured compound improves its degree of orientation to [001]orientation, that is, degree of c-axis orientation. Namely, c-axis ofbismuth layer-structured compound is vertically oriented to substrate 4to form dielectric thin-film 8.

[0054] In the present invention, it is particularly preferable that thedegree of c-axis orientation for the bismuth layer-structured compoundis 100%, however, the degree of c-axis orientation may not be complete100%. Preferably 80% or more, more preferably, 90% or more, the mostpreferably, 95% or more of the bismuth layer-structured compound may bec-axis oriented. For instance, when bismuth layer-structured compound isc-axis oriented using substrate 4 which is composed of amorphousmaterial such as glass, the degree of c-axis orientation of the bismuthlayer-structured compound may be preferably 80% or more. Moreover, whenbismuth layer-structured compound is c-axis oriented by the use offollowing thin-film forming method of every kind, the degree of c-axisorientation of the bismuth layer-structured compound may be preferably90% or more, more preferably, 95% or more.

[0055] In here, the degree of c-axis orientation(F) of bismuthlayer-structured compound can be found by the formula:F(%)=(P-P0)/(1-P0)×100 . . . (formula 1) wherein P0 is X-ray diffractionstrength for c-axis of perfectly random oriented polycrystal and P ispractical X-ray diffraction strength for c-axis. In formula 1, P is({ΣI(001)/ΣI(hkl)}) showing the ratio ofthe sum Σ I(001) of reflectingstrength I(001) from (001) surface to the sum ΣI(hkl) of reflectingstrength I(hkl) from each crystal surface(hkl) and P0 is the same.However, in formula 1, X-ray diffraction strength P when 100% c-axisoriented is 1. And by formula 1, when perfectly random oriented(P=P0),F=0% and when perfectly oriented to c-axis orientation(P=1), F=100%.

[0056] Further, c-axis of the bismuth layer-structured compoundsignifies an orientation which a pair of (Bi₂O₂)²⁺ layers are connectedto, that is, [001] orientation. In this way, as bismuth layer-structuredcompound is c-axis oriented, dielectric characteristic of dielectricthin-film 8 give its full ability. That is, even making thickness ofdielectric thin-film 8 further thinner, such as 100 nm or less,relatively high dielectric constant and low-loss(tan δ is low) can beprovided. And it also provides superior leak property, improvedbreak-down voltage, superior temperature characteristic of dielectricconstant and superior surface smoothness property. When tan δ decreases,loss Q(1/tan δ) value increases.

[0057] In above formula, when symbol “m” is an odd number, it is notparticularly limited. When symbol “m” is an odd number, polarizationaxis to c-axis orientation also exists and in comparison to when “m” isan even number, dielectric constant at Curie point increases. Further,temperature characteristic of dielectric constant, in comparison to when“m” is an even number, tends to deteriorate. However, bettercharacteristic is shown in comparison to those when conventional BST isused. Particularly, by increasing the value of symbol “m”, further riseof dielectric constant can be expected.

[0058] In above formula, the symbol “A” is composed of at least oneelement selected from Na, K, Pb, Ba, Sr, Ca and Bi. Further, when thesymbol “A” is composed of two or more elements, the ratio of thoseelements is optional.

[0059] In above formula, the symbol “B” is composed of at least oneelement selected from Fe, Co, Cr, Ga, Ti, Nb, Ta, Sb, V, Mo and W.Further, when the symbol “B” is composed of two or more elements, theratio of those elements is optional.

[0060] Dielectric thin-film 8, to said bismuth layer-structuredcompound, further include at least one element(rare-earth element: Re)selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,Yb and Lu is preferable. Substitution amount by rare-earth elementvaries by the value of “m”, for instance, when “m”=3 in formula:Bi₂A_(2−X)Re_(X)B₃O₁₂, 0.4≦x≦1.8 is preferable, and 1.0≦x≦1.4 is morepreferable.

[0061] Due to substitution of rare-earth element within this range,Curie temperature(temperature of phase transition from ferroelectric toparaelectric) of dielectric thin-film 8 can be kept, preferably, −100°C. or more to 100° C. or less, more preferably −50° C. or more to 50° C.or less. When Curie point is −100° C. to +100° C., dielectric constantof dielectric thin-film 8 increases. Curie temperature can be measuredby DSC(differential scanning calorimetry) or so. Further, when Curiepoint is less than ambient temperature(25° C.), tan δ further decreasesand consequently, the loss Q value further increases.

[0062] Further, dielectric thin-film 8, even without rare-earth elementRe, is superior in leak characteristic as following. However, withsubstitution of Re, leak characteristic can be further superior.

[0063] For instance, in dielectric thin-film 8 without rare-earthelement: Re, leak current measured when 50 kV/cm field intensity can bepreferably 1×10⁻⁷ A/cm² or less, more preferably 5×10⁻⁸ A/cm² or less,further, short ratio can be preferably 10% or less, more preferably, 5%or less.

[0064] To the contrary, in dielectric thin-film 8 with rare-earthelement Re, leak current measured under the same condition can bepreferably 5×10⁻⁸ A/cm² or less, more preferably 1×10⁻⁸ A/cm² or less,further, short ratio can be preferably 5% or less, more preferably, 3%or less.

[0065] Dielectric thin-film 8 has preferably film thickness of 200 nm orless and considering higher capacitance, more preferably those of 100 nmor less. Further, the minimum of film thickness, considering insulatingcharacter of film, is preferably about 30 nm.

[0066] At dielectric thin-film 8, for instance, surface roughness(Ra)based upon JIS-B0601 is preferably 2 nm or less, more preferably 1 nm orless.

[0067] At dielectric thin-film 8, dielectric constant at 25° C.(ambienttemperature) and 100 kHz(AC20 mV) metering frequency is preferably morethan 200, more preferably 250 or more.

[0068] At dielectric thin-film 8, tan δ at 25° C. (ambient temperature)and 100 kHz(AC20 mV) metering frequency is preferably 0.02 or less, morepreferably 0.01 or less. Further, the loss Q value is preferably 50 ormore, more preferably 100 or more.

[0069] At dielectric thin-film 8, even when frequency at particulartemperature(ex. 25° C.) is changed to high frequency domain, such asabout 1 MHz, dielectric constant change(particularly a decline) issmall. Concretely, for instance, at specific temperature, ratio ofdielectric constant value at high frequency domain of 1 MHz and those atlower than above frequency domain of 1 kHz can be 0.9 to 1.1 in absolutevalue. Namely, frequency characteristic is satisfactory.

[0070] In dielectric thin-film 8, even when metering voltage(impressedvoltage) at specific frequency(ex. 10 kHz, 100 kHz or 1 MHz) is changedto about 5V or so, dielectric constant change is small. Concretely, forinstance, at specific frequency, ratio of dielectric constant value atmetering voltage of 0.1V and those at metering voltage of 5V can be 0.9to 1.1. Namely, voltage characteristic is satisfactory.

[0071] Such dielectric thin-film 8 can be formed by thin-film formingmethod of every kind such as vacuum evaporation method, high frequencysputtering method, pulsed laser deposition method(PLD), MOCVD(MetalOrganic Chemical Vapor Deposition)method or sol-gel method.

[0072] In the present embodiment, by the use of such as substrateoriented to specific orientation(such as [100] orientation), dielectricthin-film 8 is formed. In respect to lower the manufacturing cost, usingsubstrate 4 composed of amorphous material is more preferable. Using thedielectric thin-film 8, a bismuth layer-structured compound havingspecific composition is composed by orientating to c-axis. Dielectricthin-film 8 and thin-film capacitor 2 using the dielectric thin-film 8are, even film thickness of dielectric thin-film is made thinner, suchas 100 nm or less, relatively high dielectric constant and low loss canbe provided. They can also provide superior leak property, improvedbreak-down voltage, superior temperature characteristic of dielectricconstant and superior surface smoothness property.

[0073] Further, these dielectric thin-film 8 and thin-film capacitor 2are also superior in frequency characteristic or voltage characteristic.

[0074] Second Embodiment

[0075] The present embodiment is described by exemplifying, as thin-filmcapacitance device, a thin-film multilayer capacitor forming multilayerdielectric thin-film.

[0076] As shown in FIG. 2, thin-film multilayer capacitor 20 accordingto an embodiment of the present invention includes capacitor body 22.The capacitor body 22 has multilayer structure which on the substrate 4a, a multiple number of dielectric thin-film 8 a and internal electrodethin-film 24 and 26 are alternately arranged and protection film 30 isformed to cover dielectric thin-film 8 a arranged at the most externalpart. At both ends of the capacitor body 22, a pair of externalelectrodes 28 and 29 is formed. The pair of external electrodes 28 and29 is electrically connected to each of the exposed edge faces of amultiple number of internal electrode thin-film 24 and 26 that arealternately arranged inside capacitor body 22 to form capacitor circuit.The shape of capacitor body 22 is not particularly limited but normally,rectangular parallelepiped. Further, its size is not limited but forinstance, it has about length of (0.01 to 10 mm)×width of (0.01 to 10mm)×height of (0.01 to 1 mm).

[0077] Substrate 4 a is composed of the same material as substrate 4 inabovementioned first embodiment. Dielectric thin-film 8 a is composed ofthe same material as dielectric thin-film 8 in abovementioned firstembodiment. Internal electrode thin-films 24 and 26 are composed of thesame material as lower electrode thin-film 6 and upper electrodethin-film 10 in abovementioned first embodiment. Material of externalelectrode 28 and 29 is not limited and the external electrode iscomposed of conductive oxide such as CaRuO₃ or SrRuO₃; base metal suchas Cu, Cu alloys, Ni or Ni alloys; noble metal such as Pt, Ag, Pd orAg—Pd alloys. The thickness is not limited but for instance, 10 to 1000nm or so. Material of protection film 30 is not limited but composed ofsuch as silicon oxide film or aluminum oxide film. Thin-film multilayercapacitor 20 have first layer of internal electrode thin-film 24 formedon substrate 4 a by masking with metal mask or so, then, dielectricthin-film 8 a formed on the internal electrode thin-film 24 and further,second layer of internal electrode thin-film 26 formed on the dielectricthin-film 8 a. After these processes are repeated for multiple times,dielectric thin-film 8 a arranged at the most external part and oppositeside of the substrate 4 a is covered with protection film 30. And on thesubstrate 4 a, a multiple number of internal electrode thin-film 24 and26 and dielectric thin-film 8 a alternately arranged capacitor body 22is formed. Covering the protection film 30 can decrease the effect ofmoisture in atmosphere on internal part of capacitor body 22. And whenexternal electrodes 28 and 29 are formed at both ends of the capacitor22 by dipping or sputtering or so, internal electrode thin-film 24 ofodd number layers and one side of external electrode 28 are electricallyconnected and continuity is maintained. Then, internal electrodethin-film 26 of even number layers and the other side of externalelectrode 29 are electrically connected and continuity is maintained toobtain thin-film multilayer capacitor 20.

[0078] In respect to lower the manufacturing cost, using substrate 4 acomposed of amorphous material is more preferable.

[0079] Dielectric thin-film 8 a of the present embodiment is, even whenmade thinner, relatively high dielectric constant can be provided andmoreover, surface smoothness property is satisfactory. Due to these, thenumber of laminated layers can be 20 or more, preferably 50 or more.Accordingly, thin-film multilayer capacitor 20 which may be small-sizedand relatively high capacitance can be provided.

[0080] At thin-film capacitor 2 and thin-film multilayer capacitor 20 ofthe abovementioned present embodiment, when temperature is withintemperature range of at least −55° C. to +150° C., average changerates(Δ∈) of dielectric constant is preferably within ±500 ppm/° C. (25°C. reference temperature), and more preferably within +250 ppm/° C.

[0081] Next, examples wherein the embodiment of the present invention isdescribed more specifically and the present invention will be explainedfurther in detail. Note that the present invention is not limited to theembodiments.

EXAMPLE 1

[0082] CaRuO₃ as lower electrode thin-film was epitaxial grown to [100]orientation to form SrTiO₃ single crystal substrate((100)CaRuO₃//(100)SrTiO₃) and was heated to 850° C. Then, on thesurface of CaRuO₃ lower electrode thin-film, with pulsed laserdeposition method, and by the use of SrBi₃Ti₂TaO₁₂(below also as SBTT)sintered body(This sintered body is expressed by formula:Bi₂A_(m−1)B_(m)O_(3m+3) wherein symbol “m”=3, symbol “A₂”=Sr₁, Bi₁ andsymbol “B₃”=Ti₂, Ta₁) as source material, about 200 nm film thickness ofSBTT thin-film(dielectric thin-film) was formed.

[0083] When crystal structure of SBTT thin-film was measured by X-raydiffraction(XRD), it was confirmed that this crystal structure was [001]oriented, that is, its c-axis orientation was vertical to the surface ofSrTiO₃ single crystal substrate. Further, surface roughness(Ra) of thisSBTT thin-film was measured by AFM(atomic force microscope, SPI3800;Seiko instruments made) based upon JIS-B0601.

[0084] Next, on the surface of SBTT thin-film, 0.1 mm φ Pt upperelectrode thin-film was formed by sputtering method and thin-filmcapacitor sample was manufactured.

[0085] Electric characteristics(dielectric constant, tan δ, the loss Qvalue, leak current and short ratio) and temperature characteristic ofdielectric constant for the obtained capacitor sample were evaluated.

[0086] Dielectric constant(no unit) was calculated from electrostaticcapacity, electrode dimension and interelectrode distance of capacitorsample. The electrostatic capacity was measured by using digital LCRmeter(4274A, YHP made) at capacitor sample, at ambient temperature(25°C.) and 100 kHz(AC20 mV) metering frequency.

[0087] Tan δ was measured under the same condition as aboveelectrostatic capacity was measured and the loss Q value was alsocalculated.

[0088] Leak current characteristic(Unit is A/cm²) was measured at 50kV/cm field intensity. Short ratio(Unit is %) was determined bymeasuring 20 upper electrodes and calculating the ratio of whichshort-circuit among them.

[0089] As temperature characteristic of dielectric constant, at thecapacitor sample, measuring dielectric constant under the abovementionedcondition, and when at reference temperature of 25° C., measuringaverage change rates(Δ∈) of dielectric constant to temperature withintemperature range of −55° C. to +150° C. and calculating temperaturecoefficient(ppm/° C.). The result is shown in table 1.

Comparative Example 1

[0090] Except for the use of SrTiO₃ single crystal substrate((110)CaRuO₃//(110) SrTiO₃) which CaRuO₃ as lower electrode thin-filmwas epitaxial grown to [110] orientation, in the same way as example 1,about 200 nm film thickness of SBTT thin-film(dielectric thin-film) wasformed on the surface of CaRuO₃ lower electrode thin-film. When crystalstructure of this SBTT thin-film was measured by X-ray diffraction(XRD),it was confirmed that this crystal structure was [118] oriented, and itsc-axis orientation was not vertical to the surface of SrTiO₃ singlecrystal substrate. Further, in the same way as example 1, surfaceroughness(Ra) of SBTT thin-film and also electric characteristic andtemperature characteristic of dielectric constant for the thin-filmcapacitor sample were evaluated. The result is shown in table 1.

Comparative Example 2

[0091] Except for the use of SrTiO₃ single crystal substrate((111)CaRuO₃//(111)SrTiO₃) which CaRuO₃ as lower electrode thin-film wasepitaxial grown to [111] orientation, in the same way as example 1,about 200 nm film thickness of SBTT thin-film(dielectric thin-film) wasformed on the surface of CaRuO₃ lower electrode thin-film. When crystalstructure of this SBTT thin-film was measured by X-ray diffraction(XRD),it was confirmed that this crystal structure was [104] oriented, and itsc-axis orientation was not vertical to the surface of SrTiO₃ singlecrystal substrate. Further, in the same way as example 1, surfaceroughness(Ra) of SBTT thin-film and also electric characteristic andtemperature characteristic of dielectric constant for the thin-filmcapacitor sample were evaluated. The result is shown in table 1. TABLE 1Substrate Surface Leak Short Temperature Surface Film Roughness CurrentRatio Dielectric Coefficient The Loss Orientation Orientation Ra (nm)(A/cm²) (%) Constant (ppm/° C.) tan δ Q Value Ex. 1 [100] [001] 0.5 1 ×10⁻⁸ 5 250 <±200 <0.01 >100 Comp. [110] [118] 3 5 × 10⁻⁷ 40 350±1000 >0.01 <100 Ex. 1 Comp. [111] [104] 15 5 × 10⁻⁵ 80 350 ±1000 >0.01<100 Ex. 2

[0092] As shown in Table 1, it was confirmed that c-axis orientationfilm for bismuth layer-structured compound of example 1 is inferior indielectric constant, but superior in leak characteristic. Accordingly,not only even thinner-film can be expected but higher capacitance forthin-film capacitor can be expected. Moreover, at example 1, it wasconfirmed that in comparison to the other orientation directions ofcomparative examples 1 and 2, its temperature characteristic wassuperior. Further, it was also confirmed that since Example 1 wassuperior in surface smoothness property in comparison to comparativeexamples 1 and 2, it can be preferable thin-film material formanufacturing multilayer structure. Namely, according to example 1,validity of c-axis orientation film for bismuth layer-structuredcompound was confirmed.

EXAMPLE 2

[0093] Except for forming about 35 nm film thickness of SBTTthin-film(dielectric thin-film) on the surface of CaRuO₃ lower electrodethin-film, in the same way as example 1, surface roughness(Ra) of SBTTthin-film and also electric characteristic(dielectric constant, tan δ,the loss Q value, leak current and break-down voltage) and temperaturecharacteristic of dielectric constant for the thin-film capacitor samplewere evaluated. The result is shown in table 2. Further, the break-downvoltage(Unit is kV/cm) was measured by increasing the voltage whenmeasuring leak characteristic.

EXAMPLE 3

[0094] Except for forming about 50 nm film thickness of SBTTthin-film(dielectric thin-film) on the surface of CaRuO₃ lower electrodethin-film, in the same way as example 1, surface roughness(Ra) of SBTTthin-film and also electric characteristic and temperaturecharacteristic of dielectric constant for the thin-film capacitor samplewere evaluated. The result is shown in table 2.

EXAMPLE 4

[0095] Except for forming about 100 nm film thickness of SBTTthin-film(dielectric thin-film) on the surface of CaRuO₃ lower electrodethin-film, in the same way as example 1, surface roughness(Ra) of SBTTthin-film and also electric characteristic and temperaturecharacteristic of dielectric constant for the thin-film capacitor samplewere evaluated. The result is shown in table 2. TABLE 2 Film SurfaceLeak Break-down Thickness Roughness Current Voltage DielectricTemperature The Loss (nm) Ra (nm) (A/cm²) (kV/cm) ConstantCoefficient(ppm/° C.) tan δ Q Value Ex. 2 35 0.5 4 × 10⁻⁷ >1000 250<±200 <0.04 >25 Ex. 3 50 0.5 1 × 10⁻⁷ >1000 250 <±200 <0.02 >50 Ex. 4100 0.5 3 × 10⁻⁸ >1000 250 <±200 <0.01 >100

[0096] As shown in Table 2, when film thickness for c-axis orientationfilm was made thinner, it was confirmed that although leak propertybecame little inferior, surface roughness and dielectric constant didnot change.

[0097] Further, Reference 1(Y. Sakashita, H. Segawa, K. Tominaga and M.Okada, J. Appl. Phys. 73,7857(1993)) shows the relation between filmthickness of PZT(Zr/Ti=1) thin-film which is c-axis oriented anddielectric constant. Here, the result is shown that as the filmthickness of PZT thin-film was made thinner to 500 nm, 200 nm and 80 nm,the dielectric constant(@1 kHz) decreased to 300, 250 and 100respectively. Reference 2(Y. Takeshima, K. Tanaka and Y. Sakabe, Jpn. J.Appl. Phys. 39,5389(2000)) shows the relation between film thickness ofBST(Ba:Sr=0.6:0.4) thin-film which is a-axis oriented and dielectricconstant. Here, the result is shown that as the film thickness of BSTthin-film was made thinner to 150 nm, 100 nm and 50 nm, the dielectricconstant decreased to 1200, 850 and 600 respectively. Reference 3(H. J.Cho and H. J. Kim, Appl. Phys. Lett. 72,786(1998)) shows the relationbetween film thickness of BST(Ba:Sr=0.35:0.65) thin-film which is a-axisoriented and dielectric constant. Here, the result is shown that as thefilm thickness of BST thin-film was made thinner to 80 nm, 55 nm and 35nm, the dielectric constant(@10 kHz) decreased to 330, 220 and 180respectively.

[0098] Moreover, it was confirmed that even with 35 nm film thickness ofexample 2, 1000 kV/cm or more break-down voltage could be obtained.Accordingly, materials of the present invention can be considered aspreferable for thin-film capacitor.

[0099] Further, since surface smoothness property was superior, they canbe preferable thin-film material for manufacturing multilayer structure.

EXAMPLE 5

[0100] In the same way as example 1, Curie point of SBTT thin-film andelectric characteristics(dielectric constant, tan δ and the loss Qvalue) of thin-film capacitor sample were evaluated except for thefollowings. As source material for pulsed laser deposition method,Sr_(X)Bi_(4−X)Ti_(3−X)Ta_(X)O₁₂(SBTT) sintered body(This sintered bodyis expressed by formula: Bi₂A_(m−1)B_(m)O_(3m+3) wherein symbol “m”=3,symbol “A₂”=Sr_(X), Bi_(2−X) and symbol “B₃”=Ti_(3−X), Ta_(X). Here, “x”is changed to 0.4, 0.6, 0.8, 1.0 and 1.2.) was used and about 50 nm filmthickness of SBTT thin-film(dielectric thin-film) was formed. Theresults are shown in Table 3.

[0101] Further, Curie point(Unit is ° C.) of dielectric thin-film isobtained by temperature change of dielectric constant. TABLE 3Composition Curie Point Dielectric The Loss Q (x =) (° C.) Constant tanδ Value Ex. 5 0.4 500 150 <0.02 >50 Ex. 5 0.6 350 170 <0.025 >40 Ex. 50.8 200 200 <0.05 >20 Ex. 5 1.0 50 250 <0.02 >50 Ex. 5 1.2 <−55 220<0.01 >100

[0102] As shown in Table 3, when composition “x” for c-axis orientationfilm of SBTT increased, Curie point decreased and dielectric constant atambient temperature(25° C.) increased. When composition “x” was about 1,Curie point was around ambient temperature, and dielectric constant atambient temperature was at maximum. Accordingly, when composition “x”was about 1 or more, it became paraelectric phase at ambient temperaturethat the loss Q value increased. Namely, it was confirmed that, whenhigh capacitance was required, composition range of 1.0<x<1.2 wassuitable.

EXAMPLE 6

[0103] In the same way as example 1, Curie point of LBT thin-film andelectric characteristics(dielectric constant, tan δ and the loss Qvalue) of thin-film capacitor sample were evaluated except for thefollowings. As source material for pulsed laser deposition method,rare-earth element of La added La_(X)Bi_(4−X)Ti₃O₁₂(LBT) sinteredbody(This sintered body is expressed by formula: Bi₂A_(m−1)B_(m)O_(3m+3)wherein symbol “m”=3, symbol “A₂”=Bi_(2−X), La_(X) and symbol “B₃”=Ti₃.Here, “x” is changed to 0, 0.4, 0.6, 0.8, 1.0, 1.2 and 1.4.) was usedand about 50 nm film thickness of LBT thin-film(dielectric thin-film)was formed. The results are shown in Table 4. TABLE 4 Composition CuriePoint Dielectric The Loss Q (x =) (° C.) Constant tan δ Value Ex. 6 0700 140 <0.02 >50 Ex. 6 0.4 500 150 <0.02 >50 Ex. 6 0.6 400 160<0.02 >50 Ex. 6 0.8 300 180 <0.025 >40 Ex. 6 1.0 150 200 <0.05 >20 Ex. 61.2 0 240 <0.01 >100 Ex. 6 1.4 <−55 210 <0.005 >200

[0104] As shown in Table 4, when composition “x” for c-axis orientationfilm of LBT increased, Curie point decreased and dielectric constant atambient temperature(25° C.) increased. When composition x was about 1.2,Curie point was around ambient temperature, and dielectric constant atambient temperature was at maximum. Accordingly, when composition x wasabout 1.2 or more, it became paraelectric phase at ambient temperaturethat the loss Q value increased. Namely, it was confirmed that, forneeds of high capacitance, composition range of 1.0<x<1.4 was suitable.

EXAMPLE 7

[0105] First, SrTiO₃ single crystal substrate(thickness of 0.3 mm) 4a(See FIG. 2, the same for following), which was [100] oriented, wasprepared. And on the substrate 4 a, by masking with metal mask of givenpattern, with pulsed laser deposition method, 100 nm film thickness ofCaRuO₃ made electrode thin-film as internal electrode thin-film 24 wasformed(pattern 1).

[0106] Second, with pulsed laser deposition method, on the whole surfaceof substrate 4 a including internal electrode thin-film 24, SBTTthin-film as dielectric thin-film 8 a was formed in the same way asexample 1, except film thickness was 100 nm. When crystal structure ofthis SBTT thin-film was measured by X-ray diffraction(XRD), it wasconfirmed that this crystal structure was [001] oriented, that is,oriented to c-axis. Surface roughness(Ra) of the SBTT thin-film was, bymeasuring in the same way as example 1, 0.5 nm that was superior insurface smoothness property.

[0107] Third, on the SBTT thin-film, by masking with metal mask of givenpattern, with pulsed laser deposition method, 100 nm film thickness ofCaRuO₃ made electrode thin-film as internal electrode thin-film 26 wasformed(pattern 2).

[0108] Forth, with pulsed laser deposition method, on the whole surfaceof substrate 4 a including internal electrode thin-film 26, SBTTthin-film as dielectric thin-film 8 a was formed again in the same wayas example 1, except film thickness was 100 nm.

[0109] By repeating these processes, 20 layers of SBTT thin-film werelaminated. And the surface of dielectric thin-film 8 a arranged at themost external part was covered with protection film 30 which is composedof silica to obtain capacitor body 22.

[0110] Next, at both ends of the capacitor body 22, a pair of externalelectrodes 28 and 29 composed of Ag is formed to obtain rectangularparallelepiped configuration of thin-film multilayer capacitor samplehaving length of 1 mm×width of 0.5 mm×thickness of 0.4 mm.

[0111] Electric characteristic(dielectric constant, dielectric loss, Qvalue, leak current and short ratio) of obtained capacitor sample wereevaluated in the same way as example 1. The results were 250 dielectricconstant, 0.01 tan δ, 100 loss Q value and 1×10⁻⁷ A/cm² leak current andwere satisfactory. Further, temperature characteristic of dielectricconstant for capacitor sample was evaluated in the same way as example 1and its temperature coefficient was 190 ppm/° C.

EXAMPLE 8

[0112] In the same way as example 6, capacitor sample was manufacturedand electric characteristics(leak current and short ratio) of thecapacitor sample were evaluated. The results are shown in Table 5. TABLE5 Composition Leak Current Short Ratio (x =) (A/cm²) (%) Ex. 7 0 1 ×10⁻⁷ 10 Ex. 7 0.4 5 × 10⁻⁸ 5 Ex. 7 0.6 4 × 10⁻⁸ 5 Ex. 7 0.8 4 × 10⁻⁸ 5Ex. 7 1.0 5 × 10⁻⁸ 5 Ex. 7 1.2 5 × 10⁻⁸ 5 Ex. 7 1.4 5 × 10⁻⁸ 5

[0113] As shown in Table 5, when composition “x” for c-axis orientationfilm of LBT increased, leak current decreased and short ratio decreased.Namely, it was confirmed that, in order to improve leak characteristic,composition range of 0.4<x<1.4 was suitable.

EXAMPLE 9

[0114] In the present invention, thin-film capacitor sample manufacturedat example 1, frequency characteristic and voltage characteristic wereevaluated.

[0115] Frequency characteristic was evaluated as following. At thecapacitor sample, by changing frequency from 1 kHz to 1 MHz at ambienttemperature(25° C.), electrostatic capacity was measured and alsodielectric constant was calculated. The results are shown in FIG. 3. Forthe measurement of electrostatic capacity, LCR meter was used. As shownin FIG. 3, even changing frequency to 1 MHz at specific temperature, itwas confirmed that dielectric constant value does not change. Namely, itwas confirmed that frequency characteristic is superior.

[0116] Voltage characteristic was evaluated as following. At thecapacitor sample, by changing metering voltage(impressed voltage) atspecific frequency(100 kHz) from 0.1V(50 kV/cm electrolytic strength) to5V(250 kV/cm electrolytic strength), electrostatic capacity wasmeasured(Metering temperature was 25° C.) at specific voltage and alsodielectric constant was calculated. The results are shown in FIG. 4. Forthe measurement of electrostatic capacity, LCR meter was used. As shownin FIG. 4, even changing metering voltage to 5V at specific frequency,it was confirmed that dielectric constant value does not change. Namely,it was confirmed that voltage characteristic is superior.

EXAMPLE 10

[0117] Heating single crystal silicon (100) substrate at 600° C., on thesubstrate, by pulsed laser deposition method and using Bi₄Ti₃O₁₂(Below,also as BiT) sintered body(This sintered body is expressed by formula:Bi₂A_(m−1)B_(m)O_(3m+3) wherein symbol “m”=3, symbol “A₂”=Bi₂ and symbol“B₃”=Ti₃.) as source material, about 50 nm film thickness of BiTthin-film(high dielectric constant insulating film) was formed.

[0118] When crystal structure of this BiT thin-film was measured, in thesame way as example 1, by X-ray diffraction(XRD), it was confirmed thatthis crystal structure was [001] oriented, that is, its c-axisorientation was vertical to the surface of single crystal siliconsubstrate. Further, surface roughness(Ra) of this BiT thin-film wasmeasured in the same way as example 1.

[0119] Further, electric characteristics(dielectric constant, tan δ, theloss Q value, leak current and short ratio) and temperaturecharacteristic of dielectric constant for this high dielectric constantinsulating film comprising this BiT thin-film were evaluated in the sameway as example 1. The results are shown in Table 6. TABLE 6 Film SurfaceLeak Break-down Thickness Roughness Current Voltage DielectricTemperature The Loss (nm) Ra (nm) (A/cm²) (kV/cm) ConstantCoefficient(ppm/° C.) tan δ Q Value Ex. 10 50 2 1 × 10⁻⁷ >500 100 <±300<0.02 >50 Ex. 12 50 1 5 × 10⁻⁸ >1000 200 <±200 <0.01 >100

EXAMPLE 11

[0120] In the same way as example 10, dielectric constant and leakcurrent for high dielectric constant insulating film were obtainedexcept for the followings. As source material for pulsed laserdeposition method, rare-earth element of La addedLa_(X)Bi_(4−X)Ti₃O₁₂(LBT) sintered body(This sintered body is expressedby formula: Bi₂A_(m−1)B_(m)O_(3m+3) wherein symbol “m”=3, symbol“A₂”=Bi_(2−X), Lax and symbol “B₃”=Ti₃. Here, “x” is changed to 0, 0.2,0.4 and 0.6.) was used and about 50 nm film thickness of LBTthin-film(high dielectric constant insulating film) was formed. Theresults are shown in Table 7. TABLE 7 Dielectric Leak CurrentComposition Constant (RT) (A/cm²) (x =) @ 100 kHz @ 1 V Ex. 11 0 100 1 ×10⁻⁷ Ex. 11 0.2 105 5 × 10⁻⁸ Ex. 11 0.4 110 3 × 10⁻⁸ Ex. 11 0.6 120 3 ×10⁻⁸

[0121] As shown in Table 7, it was confirmed that, as content ofrare-earth elements at LBT thin-film(high dielectric constant insulatingfilm) increased, dielectric constant increased and leak currentdecreased. Namely, it was confirmed that, high dielectric constantinsulating film of the invention is suitable for a gate insulating film.

EXAMPLE 12

[0122] On the surface of lower electrode thin-film, by pulsed laserdeposition method and using Ba₂Bi₄Ti₅O₁₈(Below, also as B₂BT) sinteredbody(This sintered body is expressed by formula: Bi₂A_(m−1)B_(m)O_(3m+3)wherein symbol “m”=5, symbol “A₄”=Ba₂, Bi₂ and symbol “B₅”=Ti₅.) assource material, about 50 nm film thickness of B₂BT thin-film(highdielectric constant insulating film) was formed.

[0123] When crystal structure of this B₂BT thin-film was measured byX-ray diffraction(XRD), it was confirmed that this crystal structure was[001] oriented, that is, its c-axis orientation was vertical to thesurface of SrTiO₃ single crystal substrate. Further, surfaceroughness(Ra) of this B₂BT thin-film was measured in the same way asexample 1.

[0124] Further, electric characteristics(dielectric constant, tan δ, theloss Q value, leak current and short ratio) and temperaturecharacteristic of dielectric constant for this high dielectric constantinsulating film comprising this B2BT thin-film were evaluated in thesame way as example 1. The results are shown in Table 6.

[0125] Note that embodiments and examples of the present invention wereexplained above, however, the present invention is not limited to theabove embodiments nor examples and may be modified in various wayswithin the scope of the invention.

1. A thin-film capacitance device composition including a bismuthlayer-structured compound whose c-axis is oriented vertically to asubstrate surface, wherein said bismuth layer-structured compound isexpressed by a formula: (Bi₂O₂)²⁺(A_(m−1)B_(m)O_(3m+1))²⁻ orBi₂A_(m−1)B_(m)O_(3m+3) in which symbol “m” is selected from oddnumbers, symbol “A” is at least one element selected from Na, K, Pb, Ba,Sr, Ca and Bi and symbol “B” is at least one element selected from Fe,Co, Cr, Ga, Ti, Nb, Ta, Sb, V, Mo and W.
 2. The thin-film capacitancedevice composition as in claim 1, characterized in degree of c-axisorientation for said bismuth layer-structured compound is 80% or more.3. The thin-film capacitance device composition as in claim 1, furtherincludes rare-earth element(at least one element selected from Sc, Y,La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb and Lu).
 4. Thethin-film capacitance device composition as in claim 3, wherein whensaid rare-earth element is “Re” and said bismuth layer-structuredcompound is expressed by formula: Bi₂A_(−1−x)Re_(x)B_(m)O_(3m+3), said“x” is 0.4 to 1.8.
 5. The thin-film capacitance device composition as inclaim 1, wherein Curie temperature is −100° C. or more to 100° C. orless.
 6. The thin-film capacitance device composition as in claim 1,wherein “m” in the formula composing said bismuth layer-structuredcompound is any one of 1, 3, 5 and
 7. 7. A thin-film capacitance devicecomprising lower electrode, dielectric thin-film and upper electrodeformed one by one on a substrate, wherein said dielectric thin-film iscomposed of thin-film capacitance device composition, the thin-filmcapacitance device composition include a bismuth layer-structuredcompound whose c-axis is oriented vertically to the substrate surface,and the bismuth layer-structured compound is expressed by a formula:(Bi₂O₂)²⁺(A_(m−1)B_(m)O_(3m+1))²⁻ or Bi₂A_(m−1)B_(m)O_(3m+3) whereinsymbol “m” is selected from odd numbers, symbol “A” is at least oneelement selected from Na, K, Pb, Ba, Sr, Ca and Bi and symbol “B” is atleast one element selected from Fe, Co, Cr, Ga, Ti, Nb, Ta, Sb, V, Moand W.
 8. The thin-film capacitance device as in claim 7, characterizedin degree of c-axis orientation for said bismuth layer-structuredcompound is 80% or more.
 9. The thin-film capacitance device as in claim7, wherein said thin-film capacitance device composition furtherincludes rare-earth element(at least one element selected from Sc, Y,La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb and Lu).
 10. Thethin-film capacitance device as in claim 9, wherein when said rare-earthelement is “Re” and said bismuth layer-structured compound is expressedby formula: Bi₂A_(m−1−x)Re_(x)B_(m)O_(3m+3), said x is 0.4 to 1.8. 11.The thin-film capacitance device as in claim 7, wherein said thin-filmcapacitance device composition has Curie temperature of −100° C. or moreto 100° C. or less.
 12. The thin-film capacitance device as in claim 7,wherein said substrate is composed of amorphous material.
 13. Thethin-film capacitance device as in claim 7, wherein thickness of saiddielectric thin-film is 5 to 1000 nm.
 14. The thin-film capacitancedevice as in claim 7, wherein “m” in the formula composing said bismuthlayer-structured compound is any one of 1, 3, 5 and
 7. 15. The thin-filmcapacitance device as in claim 7, wherein said lower electrode is formedby epitaxial growth on said substrate to [100] orientation.
 16. Athin-film multilayer capacitor comprising multiple dielectric thin-filmsand internal electrode thin-films alternately layered on a substrate,wherein said dielectric thin-films are composed of thin-film capacitancedevice compositions, the thin-film capacitance device compositionsinclude a bismuth layer-structured compound whose c-axis is orientedvertically to the substrate surface, and said bismuth layer-structuredcompound is expressed by a formula: (Bi₂O₂)²⁺(A_(m−1)B_(3m+1))²⁻ orBi₂A_(m−1)B_(m)O_(3m−3) wherein symbol “m” is selected from odd numbers,symbol “A” is at least one element selected from Na, K, Pb, Ba, Sr, Caand Bi and symbol “B” is at least one element selected from Fe, Co, Cr,Ga, Ti, Nb, Ta, Sb, V, Mo and W.
 17. The thin-film multilayer capacitoras in claim 16, characterized in degree of c-axis orientation for saidbismuth layer-structured compound is 80% or more.
 18. The thin-filmmultilayer capacitor as in claim 16, wherein said thin-film capacitancedevice composition further includes rare-earth element(at least oneelement selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Th, Dy, Ho,Er, Tm, Yb and Lu).
 19. The thin-film multilayer capacitor as in claim18, wherein when said rare-earth element is “Re” and said bismuthlayer-structured compound is expressed by formula:Bi₂A_(m−1−x)Re_(x)B_(m)O_(3m+3), said x is 0.4 to 1.8.
 20. The thin-filmmultilayer capacitor as in claim 16, wherein said thin-film capacitancedevice composition has Curie temperature of −100° C. or more to 100° C.or less.
 21. The thin-film multilayer capacitor as in claim 16,characterized in said internal electrode thin-film is composed of noblemetal, base metal or conductive oxide.
 22. The thin-film multilayercapacitor as in claim 16, wherein said substrate is composed ofamorphous material.
 23. The thin-film multilayer capacitor as in claim16, wherein thickness of said dielectric thin-film is 5 to 1000 nm. 24.The thin-film multilayer capacitor as in claim 16, wherein “m” in theformula composing said bismuth layer-structured compound is any one of1, 3, 5 and
 7. 25. The thin-film multilayer capacitor as in claim 16,wherein said internal electrode thin-film is formed to [100]orientation.
 26. A dielectric thin-film composition for capacitorincluding a bismuth layer-structured compound whose c-axis is orientedvertically to a substrate surface, wherein said bismuth layer-structuredcompound is expressed by a formula: (Bi₂O₂)²⁺(A_(m−1)B_(m)O_(3m+))²⁻ orBi₂A_(m−1)B_(m)O_(3m+3) in which symbol “m” is selected from oddnumbers, symbol “A” is at least one element selected from Na, K, Pb, Ba,Sr, Ca and Bi and symbol “B” is at least one element selected from Fe,Co, Cr, Ga, Ti, Nb, Ta, Sb, V, Mo and W.
 27. The dielectric thin-filmcomposition for capacitor as in claim 26, characterized in degree ofc-axis orientation for said bismuth layer-structured compound is 80% ormore.
 28. The dielectric thin-film composition for capacitor as in claim26, further including rare-earth element(at least one element selectedfrom Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb andLu).
 29. The dielectric thin-film composition for capacitor as in claim26, wherein Curie temperature is −100° C. or more to 100° C. or less.30. A thin-film capacitor comprising lower electrode, dielectricthin-film and upper electrode formed one by one on a substrate, whereinsaid dielectric thin-film is composed of dielectric thin-filmcomposition, the dielectric thin-film composition include a bismuthlayer-structured compound whose c-axis is oriented vertically to thesubstrate surface, and the bismuth layer-structured compound isexpressed by a formula: (Bi₂O₂)²⁺(A_(m−1)B_(m)O_(3m+1))²⁻ orBi₂A_(m−1)B_(m)O_(3m+3) wherein symbol “m” is selected from odd numbers,symbol “A” is at least one element selected from Na, K, Pb, Ba, Sr, Caand Bi and symbol “B” is at least one element selected from Fe, Co, Cr,Ga, Ti, Nb, Ta, Sb, V, Mo and W.
 31. The thin-film capacitor as in claim30, characterized in degree of c-axis orientation for said bismuthlayer-structured compound is 80% or more.
 32. The thin-film capacitor asin claim 30, wherein said dielectric thin-film composition furtherincludes rare-earth element(at least one element selected from Sc, Y,La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb and Lu).
 33. Thethin-film capacitor as in claim 30, wherein said dielectric thin-filmcomposition has Curie temperature of −100° C. or more to 100° C. orless.
 34. A high-dielectric constant insulating film including a bismuthlayer-structured compound whose c-axis is oriented vertically to asubstrate surface, wherein, said bismuth layer-structured compound isexpressed by a formula: (Bi₂O₂)²⁺(A_(m−1)B_(m)O_(3m+1))²⁻ orBi₂A_(m−1)B_(m)O_(3m+3) wherein symbol “m” is selected from odd numbers,symbol “A” is at least one element selected from Na, K, Pb, Ba, Sr, Caand Bi and symbol “B” is at least one element selected from Fe, Co, Cr,Ga, Ti, Nb, Ta, Sb, V, Mo and W.
 35. The high-dielectric constantinsulating film as in claim 34, characterized in degree of c-axisorientation for said bismuth layer-structured compound is 80% or more.36. The high-dielectric constant insulating film as in claim 34, whereinsaid bismuth layer-structured compound further include rare-earthelement(at least one element selected from Sc, Y, La, Ce, Pr, Nd, Pm,Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb and Lu).
 37. The high-dielectricconstant insulating film as in claim 36, wherein when said rare-earthelement is “Re” and said bismuth layer-structured compound is expressedby formula: Bi₂A_(m−1−x)Re_(x)B_(m)O_(3m+3), said x is 0.4 to 1.8.